Electric cable



April 18, 1933. u o. SMARKUSON j 1,904,873

ELECTRIC CABLE Filed Jan. 2, 1926 //7 venfar 0504/ 6. Mafia/m1 PatentedApr. 18, 1933 UNITED STATES PATENT OFFICE OSCAR SEVERIN IARKUBON, OFHILTON, NEW JERSEY, ASSIGNOR TO WESTERN ELEC- TRIO COMPANY,moonrona'rnn, 0] NEW YORK, N. Y., A CORPORATION OF NEW YORK ELECTRICCABLE Application filed January 2, 1928. Serial No. 78,798.

This invention relates to electric cables, and more particularly to thetype employed for the transmission of intelligence telephonically.

It has been the practice in some instances in connection with themanufacture of telephone cables to form the cable by stranding pairs ofpaper insulated conductors together, binding the thus formed conductorsand finally extruding a sheath of lead over the insulated conductors.This type of construction embodies certain outstanding features, namely,the high cost of the lead sheath and the inherent characteristics ofthelead sheath to react deleteriously when subjected to chemical andelectrolytic action. It is therefore the object of the present inventionto construct a cable which may be manufactured economically and issubstantially unaffected by electrolysis as well as being considerablylighter in weight than cables 0 the foregoing construction.

According to one embodiment the present invention contemplates atelephone cable constructed by arranging a lurality of paper insulatedconductors of low resistance stranded together with a thin sheath ofmetal, preferably of lead alloy tape, associated therewith to protectthe conductors against electrical inductive interference and to increasethe mechanical strength of the cable and a covering of material which isimpervious to moisture.

Other objects and advantages of this invention will more fully appearfrom the following detailed description taken in connection with theaccompanying drawing illustrating the embodiments thereof, in which Fig.1 is an elevation, partly in section, showing the preferred form of theimproved telephone cable;v

Fig. 2 is an elevation, showing another form of phone cable;

Fig. 3 is a vertical sectional view along the line of 33 of Fig. 1; and

Fig. 4 is a vertical sectional view along the line of 4-4 of Fig. 2.

Referrin to the drawing (Figs. land 3), the numer 10 indicates aplurality of low refpartly in section,

e improved teleother.

sistance copper wires insulated with paper, cotton, silk or othersuitable material, usually twisted together in pairs, the pairs beingstranded together loosel in layers to form a group or bundle 12. 'l hegroup 12 may be formed in any suitable manner, but preferably by theusual and well known form of strander, which has associated therewith atape serving head by whicha paper wrapping 14 may be applied spirally toretain the oup comprising the conductors within a pre etermineddiameter. Surrounding the paper wrapping 14 is a flexible sheath 15which is formed by applying a comparatively thin metallic ribbon ortape, preferably composed of lead alloy, spirally around the cablesothat the edges of ad acent turns slightly overlap each The sheath 15serves as a shield for the cable circuits against extraneous inductiveinterference, thus providing the cable circuits with more stableelectrical characteristics, and also mechanically strengthens the cable.A covering 16 of tough rubber, gutta rcha or a gutta percha substitute,such as entzschs compound, may then be applied by drawing the conductorsthrough an extruding machine, which may be of the usual type whichapplies the covering in one or more layers around the entire length ofthe thus arran (1 conductors.

e cable illustrated in Figs. 1 and 3 described in the foregoingdescription is of particular utility where telephone cables are employedin underground systems which is the principal type of construction usedin large cities. The employment of an outer imperforate non-metalliccoverin 16 of the character described, instead 0 the usual lead sheath,generally employed in cables of this type, mlnimizes damage to the cablefrom e ectrolytic action to which lead is particularly susceptible dueto the decomposition resulting when subjected to a neighboring source ofelectrical energy. It also results in a cable which may be manufacturedeconomicallK and with'a decided reduction in the weight t ereof, as willreadily be ap arent since the usual comparatively thick layer of leadforming the outer sheath of cables of this type is omitted.

In some cases it may be advantageous to employ a cable of a constructionslightly different from the type of construction heretofore described,in which case the spirally arranged sheath 15 applied directly to thepaper wrapping 14 is omitted, and the gutta percha covering 16 ispreferably provided with a protective sheath 17 (Figs. 2 and 4) composedof a thin continuous layer of lead alloy applied in a well known mannerby the usual type of extrusion press. This outer sheath 17 of leadserves as a protection to the rubber, gutta percha or gutta perchasubstitute covering 16 against water penetration and chemicaldecomposition which might take place if the covering 16 were exposeddirectly to atmospheric conditions such as is the case when the cablesare employed of the aerial or overhead construction. and also as a 20shield to the cable circuits against extraneous inductive interference.It may be preferable, in some instances to form the outer protectivesheath of wire or any suitable strand applied spirally, in a manner wellknown to form a continuous unbroken sleeve, in place of the thin layerof lead, or to apply a fabric tape composed of some such material ascotton, jute. hemp. etc., the tape being impregnated either previouslyto its application to the cable or thereafter with any suitable compoundcapable of resisting chemical decomposition due to atmosphericconditions and also serving as a mechanical reinforcement for the cable.

Vhat is claimed is:

1. A telephone cable comprising a plurality of pairs of paper'insulatedconductors, a continuous insulating sheath composed of a paper ribbonapplied spirally around the conductors, a relatively thick sheath oftough rubber applied to the outside of said paper ribbon sheath. and athin continuous lead covering surrounding the sheath of tough rubber forprotecting said conductors against extraneous electrical disturbances.

2. A telephone cable comprising a plurality of individually insulatedconductors assembled into a solid core, a continuous insulating mediumdisposed therearound to form an imperforate sheath therefor. a sheathcomposed of thin lead ribbon wrapped helically about said imperforatesheath. and a relatively thick sheathing of tough rubber formed aboutand engaging the lead sheath.

In Witness whereof. I hereunto subscribe my name this 28th day ofDecember A. D.. 1925.

OSCAR SEVERIN HARKUSON.

